1. Field of the Invention
The present invention relates to an improvement of a linear motor system having such a structure that one of a movable body and a fixed body is provided with magnetic pole teeth and the other with the teeth facing the aforesaid pole teeth a fine gap, and in which the movable body travels while the aforesaid pole teeth and teeth face each other.
2. Related Background Art
A linear motor system used for the table carrier of a conventional machine tool or the like is provided with a movable body having a plurality of magnetic pole teeth and a fixed body having a plurality of fixed teeth, and the aforesaid movable body is structured to be movable along the aforesaid fixed body (as disclosed in Japanese Patent Laid-Open Appln. No. 63-180443, for example). In the above-mentioned conventional linear motor system, a scraping member is installed on the movable body, and is slidably in contact with a dust cover for protecting the grooves between the fixed teeth of the fixed body. The scraping member acts to scrape off the dust deposited on the surface of the dust cover, thus preventing the ingression of any foreign substances such as dirt and dust into the space between the movable body and the fixed body.
Generally speaking, in order to improve the thrust in a linear motor system of the aforementioned type, the gap (space) between the magnetic pole teeth of the movable body and fixed teeth of the fixed body should desirably be narrowed. Traditionally, therefore, these bodies are constructed to face each other through a narrow gap after the surfaces of both teeth have been finished by an abrasive machining.
However, because the gap is extremely narrow, it is likely to catch dust particles, and there is a risk that surfaces of the fixed teeth of the fixed body and the magnetic pole teeth of the movable body will be damaged by the dust particles caught therebetween. In addition, the above-mentioned surfaces of the magnetic pole teeth and fixed teeth which are finished by the abrasive machining are exposed directly to the atmosphere. Therefore, corrosion or rust tends to occur on the aforesaid surfaces. Also, if this linear motor system is used in a clean room or in a vacuum, there is a problem that the exposed magnetic pole teeth and fixed teeth generate dust particles or gas.
Accordingly, in the above-mentioned conventional linear motor system, the dust cover and scraping member are provided. Nevertheless, there is still a disadvantage that the thrust of the linear motor system is reduced due to the friction resistance between the surface of the aforesaid dust cover and the above-mentioned scraping member which is slidably in contact therewith in order to prevent the ingression of the dust particles into the above-mentioned gap.